I put an OS 46FX on a Predator and you would not believe how tail-heavy it was. I was pissed off--really pissed.

I had ordered an HS-81 for the throttle and HS-225 for my elevons. RX was Hitec 555 and my RX battery was a 270mah nicd.

I ended up installing a standard size JR517 right behind the firewall to get nose weight. I crammed a 600mah battery up front too.

I had to scrap the stock servo tray and move my HS-225 servos under the wing saddle and completely rework the linkages to balance my plane.

I had to shove the fuel tank so far forward--that I needed to dremel out the front former under the LE of the wing. That was so that I could get the tank as far forward as possible.

Do I think a 61FX will make it nose heavy? NO

A 61FX w/ stock muffler weighs 7 ounces more than a 46FX with stock muffler.

I don't know what to say. Maybe I just got a plane with spruce hardwood in the tail?????????

I still have a wing and tail set for the predator. I'm going to buy a fuse cheap when one of them shows up on the TH scratch & dent page.

I'll be using a 60 size engine--and I'm confident that I won't have to make NEAR as many mods to it as my first predator with the 46FX.

RCJON--I'd bolt the engine to the firewall first and then start placing servos and other electronics in the plane. Find out where your servos, RX, battery will need to be located to balance it. You might have to make a few mods--might not. But--definetly bolt the engine up first and balance from there.

GLASS and PIN the firewall--DEFINETLY. Add tri-stock and slap some epoxy on there to coat it all and add strength.

Good luck--and for gawd sakes --put a radar on that sucker--I want to see some big numbers!!